Because the document, which received unanimous NRC support, is a draft, it is open for public comment for another 60 days before it can be finalized.

The NRC plans to hold eight regional public meetings and two nationally Webcast meetings at NRC headquarters on the proposed rule. In the Northeast, meetings have been tentatively planned for White Plains, N.Y., and North Chelmsford, Mass. in September.

Currently, the operating licenses on the Limerick plant’s two nuclear reactors expire Oct. 26, 2024, for Unit 1, and June 22, 2029, for Unit 2. Exelon has applied for a 20-year license renewal for each reactor.

“Limerick Generating Station has had a history of safe and reliable operations since it opened in 1986. Limerick’s license renewal application is one of the nation’s strongest, due, in part to the station’s commitment to environmental protection and safety,” Dana Melia, the plant’s communications manager, wrote in an email responding to a Mercury request for comment on the NRC’s issuance of the draft rule and its impact on Exelon’s renewal application.

“We are committed to maintaining a legacy of safe operations, including the storage of spent nuclear fuel, while the Department of Energy and Congress seek a long-term repository for spent fuel,” Melia wrote.

Called the draft rule and Generic Environmental Impact Statement, the draft NRC document analyzes the environmental impacts of continued storage of spent nuclear fuel at nuclear plants.

Although no longer hot enough to use in the reactor, nuclear fuel rods remain radioactive for hundreds of years, even after they are moved from pools, where they are left for several years to cool, into the steel and concrete “dry cask storage” drums that can now be found at nuclear plants all over the country, including at Exelon Nuclear’s Limerick Generating Station.

“Although the environmental impact of spent nuclear fuel storage during the licensed life for operation may be site specific, the impacts of continued storage may be addressed generically because” previous experience has taught operators and the NRC what environmental impacts to expect, which makes them reasonably predictable and those issues are “sufficiently gradual and predictable to be addressed generically.”

The assumption that spent nuclear fuel can be stored safely on site depends largely on the NRC’s new assumption that a national depository for the substance will be established within 160 years.

“In terms of our review of the Limerick license renewal application, the approval of the Draft Generic Environmental Impact Statement (GEIS) is consistent with our earlier projected timeline,” NRC spokesman Neil Sheehan wrote in an e-mail responding to Mercury inquiries.

“The Commission last year ordered that no final decisions be issued on license renewal or new reactor applications until the Waste Confidence Decision environmental review is completed, which is expected to occur sometime in late summer 2014. In addition, the hearing process for the Limerick application has not yet been concluded,” Sheehan wrote.